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362

MR. HOWARD'S REJOINDER TO MR. SYMINGTON.

the best and next best suggestions as to the cause and method of preventing the recurrence of steam-boiler explosions. It was understood, that no fewer than seventy-four plans, suggestions, essays, and lectures were handed in, but the matter has not gone farther, at least the plans have not been made public, which is much to be regretted, for from among the mass of useless matter which would be produced, surely something towards effecting a cure would have come out.

My object in noticing this subject is to offer some remarks on the subject of "foaming," known by the name of" priming" in this country. As far as I can see, the Committee of the Franklin Institute have elicited nothing as to the cause of this phenomenon, nor given any cure for it. They notice a very feasible plan by Mr. Ewbank (the perforated steam-pipe), but they do not tell if it prevents the foaming. Every person conversant with high-pressure engines knew perfectly without looking in at a window that a foaming commenced when the engine began to work, and that the gage-cocks at that time would blow water, although the floats indicated the water-line to be considerably lower. I have a large high-pressure engine underground here, and I have been more than commonly annoyed with priming, and have tried various methods, but without effect; in the course of working out these experiments, I have most certainly discovered the cause of the priming, but the cure, in this case, although certain, is not a convenient one. I first attempted to separate the water from the steam after it left the boiler by the means represented in the foregoing sectional view, which is on a scale of half an inch to a foot.

Above the boiler A (which is long and circular, with hemispherical ends,) was placed a vessel or separator; A a into which the steam was admitted by the pipe B, the mouth of which was twelve inches above the bottom of the vessel A; alongside of this a small pipe e, leading under the water-line, was placed, and the steam to the engine was taken from the top of the vessel A by the eductionpipe E. My idea was, that when the foam entered the separator the steam would flow off at the top, and the water would fall down by its gravity and get into the boiler again by the pipe c; but I was sadly disappointed; the engine continued to prime as bad as ever, and

the old and expensive method of putting tallow into the boiler was again resorted to. I began to observe, that for a few days after the boiler was cleaned no priming occurred, and therefore ordered the boiler to be cleaned once a week, and ever since we have had no priming but on Friday evening and Saturday after the dirt accumulates. The silt which occasions this, is the finer portions of shale taken up by the water in passing through a coal-waste; it attaches itself to the bottom and sides of the boiler in feathery flakes, which gradually extend far up above the water-line. That this is the cause of the foaming, there cannot be a doubt; for when there has been any unusual traffic in the mine from which the boiler is fed to make the water dirtier than common, then the priming begins much earlier in the week; and, moreover, I have often seen the priming produced when the boiler was clean, by peas-meal or horse-dung being put in to stop a leak. This favourite cure of our engine-men's cannot be used from the absolute certainty that the engine will prime all that and the next day (moss is found to tighten a leak without priming). It would therefore seem that this troublesome defect of many high-pressure engines arises from the river mud,* attaching itself to the sides of the boiler; but how it acts, I must leave to be settled by those who have windows to look in and see.

I trust, sir, you will give these remarks a place in your useful pages, and I shall be glad if they elicit more practical remarks on the subject; and

Your most obedient servant,
L. LANDALE.
Wemyss Cottage, July 30, 1836.

MR. HOWARD'S REJOINDER TO MR.

SYMINGTON.

Sir, In reply to Mr. Symington's last communication, I must, in the first place, freely tender my apology for stating that I had seen him at the King and Queen Iron-works, when (his own denial being quite sufficient evidence) such was not Even had it been so, I did not mean for a moment to impute to him the motive of having done so, as he suggests, I must say, gratuitonsly, for the purpose of pirating my invention. But I will ex plain. In the spring of 1834, I was em

the case.

*The comminuted shale of the mine was once fine river silt, the same as this.

RAILWAY TRANSIT AND INLAND NAVIGATION.

ployed in fitting his Majesty's steamvessel Comet with my patent vaporisers and condensers; and the Admiralty purposed trying a wheel invented by Mr. Symington at the same time. On my pointing out, however, the inconvenience and uncertainty of trial likely to result to both parties by this arrangement, it was very properly abandoned by the Admiralty, and the wheel was subsequently tried in the Alban. In the mean time I called on the manufacturer of the wheel at Bankside (Mr. Brough, if I remember the name correctly), and he came to Rotherhithe to inspect my engine at work there. Again, by appointment, he came with, and introduced to me, as I fully understood (and here must lie the error), Mr. Symington as the inventor of the wheel in question, to whom I explained my invention in every particular-the more so as he was then interested in the efficiency of it to propel his wheel. These facts will, I doubt not, give Mr. Symington a clue by which to discover the cause of my mistake.

Now to the more important point at issue between us. Will Mr. Symington state, that he does not take the same principle or method of condensation as that previously patented by me? Will he state, as he seems to insinuate, that I have not caused the process to answer completely, that is, I now say, as completely as any pre-existing plan of condensation whatever? And will he inform me where he has previously done so? Upon this evidence I will ground the validity of my claim to priority of invention.

When Mr. Watt discovered and patented the splendid improvement of condensing the steam in a vessel apart from the cylinder, he invented a principle or new method; and no subsequent alteration or even improvement upon it could deprive him of his patent right during the term for which it was granted. Whether the condenser was placed in a well or in a garret-whether the steam was condensed by injection or external cold water (a material difference)-who, even with the most contracted view of justice, would deny that he was the inventor of the process, and legally and morally entitled to the benefit of it; provided, as was the case, his own arrangement proved perfectly efficient in practice. Although I do not pretend to place my method of condensation, by withdrawing

363

the warm water from the condenser and injecting it again amidst the steam, the heat in the mean time having been abstracted from it, in competition with Mr. Watt's invention, for the result is far, very far inferior indeed, to that obtained by his improvement on the then existing steam-engine; yet I place myself on the same ground with respect to others who attempted to practise, in combination with his process, any alterations in the arrangement or details. In this position I presume Mr. Symington to stand with respect to myself.

I may further state, that my specification provides for such contingencies, otherwise a patent is mere waste parchment; and that a description of both the method of vaporisation (by far the more important, by-the-bye,) and condensation is given in the last edition of Dr. Lardner's able treatise on the steam-engine, and to which work Mr. Symington himself alludes in his communication in your No. 677. The specification further states, that the result of the plan of condensation when employed with boilers, will be a very rapid and effectual condensation of the steam, with the advantage of continually returning to the boiler the same water, or nearly so, and also a great reduction in the size of the airритр.

Your most obedient servant,
THOMAS HOWARD.

7, Tokenhouse Yard, London,
August 24, 1836.

RAILWAY TRANSIT AND INLAND NAVIGATION.

(From the Times' Report of First Day's Proceedings of the Bristol Meeting of the British Association, August 22, 1836.)

The subjects arranged for discussion were two-on certain points connected with the theory of locomotive-carriages, and on the application of our knowledge of the phenomena of waves to the improvement of the navigation of shallow rivers and canals.

Professor Mosley opened the first point by stating that there were many gentlemen present acquainted with the practical working of steam-engines, but the relations between the theory and practice were not perfectly understood. The piston of a locomotive-engine was pressed on either side, one resulting from the friction on the road, and the other from the passive friction of the engine itself. If it was lifted from the ground, a person endeavouring to move the wheels would find a resistance equal to 150lbs. The cause of the resistance was this-that the traction upon the engine induced additional friction

364

RAILWAY TRANSIT AND INLAND NAVIGATION.

of the machinery, and that probably was one-fifth of the whole amount of friction. If the engine moved without a train, there would be a passive resistance; if a train was attached to it, there would be induced a considerable friction of the machinery. There were, in fact, three causes of resistance the friction of the carriage, the passive resistance, the additional by the train according to the weight of the train. On the other side there was the expansive force of the steam. The quantity of work done was greater as the velocity was less. Inclined planes on railroads he considered to be injurious to co

-the first and lastiction

Dr. Lardner said he had given a good deal of evidence before Parliament upon this subject. In all inclined planes more steep than the angle of repose there was an unfavourable loss of power. The portion of mechanical force expended in ascending the plane was not repaid in the descent. Theoretically

they might take advantage of the accumulative matter as a deposit of momentum, and make a perfect mechanical compensation, but that was not the case in practice, because they were obliged to check the velocity in the descent. He had never said, as had been represented, that inclined planes were not of importance, because the friction in the ascent was given back in the descent. When the engine was descending, great part of its steam was going off in the safety-valve, there. fore inclined planes were injurious. All the experiments led to the conclusion, that every effort should be made to attain as perfect a level as possible. Every departure from a level, though it saved a quantity of capital in the construction of a road, entailed an everlasting expense. The result of some experiments he had made was this-that in the ordinary state of the roads, the force necessary on a level was 71bs. per ton; but he found an extraordinary difference depending on the state of the rails, a difference amounting in some instances to such an extent that the friction was reduced to 4 lbs. When it rained and the rails were wet, he found the friction reduced to 4lbs., but as soon as the rails became again dry, the friction was again 7 lbs.; he should therefore suggest, that two watering-pots should be placed before the wheels, so as to give the engine an additional power of nearly 50 per cent. There was another point with regard to dust: he had let himself down a very steep inclined plane, and when he attained a speed of 60 miles an hour, he had a quantity of sand put on the rails, and the consequence was, that the steamengine came to a stop.

As to the second subject for discussionnamely, "On the application of our knowledge of the phenomena of waves with a view to the improvement of the navigation of shallow rivers and canals."

.

Mr. Russell made some very lengthy, but very interesting observations, the substance of which was this,-where canals did exist, there was no man but wished they should be conducted in the most profitable manner. Newton's law had been confirmed, that the resistance was in proportion to the square of the velocity. The difference in the amount of resistance between a vessel drawn on a canal by a horse, trotting or cantering, was from 108 to 136. He would read from a paper the results of various experiments he had made, in which they would perceive a very curious fact as regarded the pace of eight miles an hour. The table was thus :

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Lbs.

33

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91

265

215

235

246

352

444

But at the rate of 20 miles an hour the vessel skated along the surface of the water, and there was scarcely any resistance at all. When a vessel was propelled at a great velocity and then stopped, it produced a wave varying in its form, according to the mass of the water, and he had followed such a wave a mile and a half; the velocity of the wave was uniform, and independent of the velocity of the vessel. If the vessel was going four miles an hour, this wave would go at the rate of eight miles an hour, and he had seen a large wave overtake a small wave and pass it. The waves never exceeded in height the depth of the quiescent water. Vessels at a slow velocity did not divide the water as was generally supposed, but pushed it forward in the shape of a wave; but where the velocity was greater than eight or nine miles an hour, the vessel did divide the water. It was possible to bring the vessel completely upon the wave, and then you had scarcely any resistance. A velocity of between four and six miles an hour on canals was unprofitable; beyond 11 miles an hour you had a high velocity, and comparatively little resistance. He recommended a rectangular canal where it was intended the velocity should be great, as by widening a canal with sloping banks you increased the resisting power.

The Rev. Mr. Whewell agreed with Mr. Russell in nearly all his remarks, which he considered most valuable and important to be considered. It was clearly ascertained that the greater the velocity the less the resistance.

Mr. Russell felt convinced that by adopting a considerable velocity, the Atlantic might easily be crossed with steam-vessels.

The Chairman (the Marquis of Northampton) said, that the observations of Mr. Rus

RESUSCITATED INVENTIONS.

sell were most important, and that the gratitude of the country was due to him for his experiments.

IMPROVEMENT IN NAPIER'S RODS.

(From Second Day's Proceedings.)

In the section of mechanical science, Mr. Hawkins read a paper on an improvement upon Napier's rods, for facilitating the multiplication of high numbers with little liability of error, the invention of Mr. J. N. Copham, of Bristol.

The invention consists in cutting each of Napier's rods into cubes, and in stringing the cubes together by means of pins passing through two perforations in each cube, made at right angles to each other parallel to the figured sides.

By this arrangement the cubes may be readily placed in such positions in respect to each other that the product may be obtained by addition only, without the necessity of transcribing the figures from the rods previous to the addition, thus avoiding a great liability to error, and effecting a saving of time in the calculation.

The pins are in two sets with heads of two different shapes.

On the heads of one set of pins are marked 0. 1. 2. 3. 4. 5. 6. 7. 8. 9. respectively, the same pin having the same number on each side of the head; but the number on one side of the head is inverted in respect to the position of the number on the other side.

The heads of the other set of pins are also numbered 0. 1. 2. 3. 4. 5. 6. 7. 8. 9., but the pin having 0. on one side of the head, has 9. on the other side; that having 1. on one side, has 8. on the other, &c. The figures in this set, also, are inverted in respect to those of the opposite side of the head.

The cubes are kept strung on those pins which have the same figures on each side of the head: 10 cubes on each pin representing one of Napier's rods.

On the pin marked 0. all the cubes are marked 0. on both sides.

On the pin marked 1. the cubes are marked 0. 1. 2. to 9. on one side, and 9. 8. to 0. on the other side. The numbers on the two sides of each cube, on being added together, make 9.

On the pin marked 2. the cubes are marked 0. 2. 4. 6., &c. on one side, and 18. 16., &c. on the other side. The numbers on the two sides of each cube, on being added together, make 18.

And thus the numbers on the cubes of each pin are all consecutive multiples of the numbers on the head of the pin; and the two numbers on each cube on being added together make the number on the head multiplied by nine-the numbers ascending on one side, and descending on the other.

RESUSCITATED INVENTIONS.

365

Sir, In a recent Number of The Repertory of Arts there is a copy of a specification of a patent granted to Mr. Booth for improvements in steam locomotive-carriages; one of which improvements is the "application of a throttle-valve to the eduction-pipe of the cylinders." The idea of this is not new; one of the early volumes of the Mechanics' Magazine contains an account of the application of a throttle-valve to the eductionpipe of a locomotive engine used on one of the railroads at a northern colliery several years before. The mere mention of this circumstance tends, in some measure, to show the increasing value of the Mechanics' Magazine as a record of useful and valuable inventions.

The mode of traction through canal tunnels given in a recent Number of your work (though displaying considerable ingenuity as regarding the arrangement of some of the parts) is also not new. In the year 1828, I was on board a similar sort of boat, and passed in it through the tunnel at Islington. The boat was nearly of the width of the tunnel, and its sides were protected by guard-rails; the chain (of common construction) made two or three turns round an iron roller, and passed in and out at head and stern of the boat through a wrought-iron tube. Motion was given to the said roller by a high-pressure engine of 4-horse power, the cylinder of which was fixed in a horizontal position with the usual contrivance for reversing motion. This tunnel, about 900 yards long, was traversed by this boat, with two Thames barges in tow, in about 15 minutes. Coke was chiefly used as fuel; and it is worthy of remark, that at the head of the boat the heat and sulphurous smell was intolerable, even for a few seconds. Placed at the stern, however, no other inconvenience was felt than the rush of cold air. This boat, I understand, not sufficiently remunerating the owner, was soon after discontinued, and the old and dangerous method again reverted to. The horses generally employed in towing the barges might be shipped on board a spare boat furnished with a roller and chain as above described, and their services would doubtless be eligible in towing the barges.

I am, Sir, yours, &c.

I. ELLIOTT.

366 SHORT METHOD OF CALCULATING THE CONTENTS OF VESSELS.

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METHOD OF CALCULATING THE CON-
TENTS OF VESSELS.

Sir,-In looking over some of the back volumes of your valuable miscellany, I observed in pp. 330 and 331 of vol. xvi. two methods of extracting the cube root, which I am somewhat surprised have not been noticed in some of the subsequent Numbers, more especially as the former of the two methods (Mr. Laker's), in my opinion, as well as in that of several of my acquaintance, is of great practical utility, being very concise and also ap plicable to every case that can occur; but the latter method, communicated by F. B., is impracticable, except in a very few cases, and consequently useless. This is easily proved by taking the example. illustrating the first method, when F. B. would find himself involved in literally an endless maze of figures without any

probability of obtaining the required

root.

Having also a short time since been applied to for a short method of finding the content of cisterns, &c., in gallons or bushels, by knowing the length, breadth, and depth, I naturally turned to your museum of information for the required rule, where I soon discovered in the Number for January 19, 1828, a rule apparently to the purpose; which, however, being calculated for Winchester bushels, was inapplicable to the case in point, and as no rule for finding the content in imperial measure has since ap peared, I take the liberty of offering the following formula, the insertion of which, should you deem them worthy of a place in your Magazine, will oblige,

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Short Method of finding the Content of a Parallelopipedon in Imperial Measure. Let length, b = breadth, d = depth, all in feet, and e content.

Then, if e be required in gallons

817bd

e.

13

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104 lb d 13

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If c be required in bushels, the formula becomes с Example 1.-In a tank where 7 – 6 ft. 3 in., b = 3 ft. 3 in., and d≈4 ft., required 81 x 6.25 x 3.25 × 4

× 8 × 4 × 3
13

the content in imperial gallons:5061 gallons, the content. Example 2.--Required the content in imperial bushels of a corn-bin, when 18 ftug 10 b=4 ft., and d 3 ft. :

13

74 bushels, the content.

101b d 13

In some cases the readiest method for bushels will be found to be nearly; then to every 10 bushels thus found add 1 gallon.

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